Description

I was using the EntityGenerator to create class files from yaml when I realized php warnings like `PHP Warning: Illegal string offset 'name'` on the console. Warnings have also been emitted for the `type` and `length` fields.

The generated php file also contained a wrong annotation for the discriminator column:

@ORM\DiscriminatorColumn(name="s", type="s", length=s)

The single change in this pull request resolves the problem, so even the warnings disappear and the generated file contains the proper annotation.